1. Field
Exemplary embodiments of the present invention relate to a method for operating a non-volatile memory device, and more particularly, to an erasing method of a non-volatile memory device.
2. Description of the Related Art
A non-volatile memory device retains data stored therein although power is turned off. Diverse non-volatile memory devices including a NAND-type flash memory are applied to various systems and devices.
In the non-volatile memory device, a program operation for storing a data in a memory cell and a read operation for reading a data stored in a memory cell are generally performed on the basis of a page, while an erase operation for deleting a data stored in a memory cell is performed on the basis of a block.
Meanwhile, a non-volatile memory device is required to operate in a limited number of erase-program cycles to reliably store data. This is because memory cells are deteriorated as the erase operation and the program operation are performed repeatedly. Since an erase operation is always performed before a program operation, the number of the cycles of the program operations and the number of the cycles of the erase operations are the same.
However, since the erase operation is performed on a block basis whereas the program operation is performed on a page basis, if a data of one page in any one block is corrected, the entire block including the page is erased. This increases the number of erase-program cycles of the non-volatile memory device, eventually making the life-span of the non-volatile memory device short.
Therefore, Korean Patent Publication No. 10-2010-0015423 discloses a method of dividing one block into a plurality of sub-blocks and performing an erase operation on the basis of a sub-block.
According to the method, an erase operation may be performed only on the memory cells of a selected sub-block by applying an erase voltage, which is a positive high voltage, to a substrate, applying 0V to a word line of the selected sub-block, and applying a voltage that is substantially the same as the erase voltage to the other word lines.